This invention relates to a damper adhered to a head suspension of a disc drive and a head suspension having the damper.
Disc drives for rotating a recording disc, such as a hard disc drive and a magnetooptical disc drive, have a read/write head part. As shown in FIG. 2A, the head part is made up of a head 1 (e.g., a magnetic head or an optical head) and a head suspension 2 supporting the head 1. Numeral 3 is a block on which the head suspension is fixed.
Since the head portion directly receives air pressure from a rotating disc and vibrations transmitted from the drive of the head 1 or the motor for rotating the disc, it follows that the head suspension 2 formed of a leaf spring, etc. is deformed to shift the position of the head 1, causing reading or writing errors.
In order to damp the vibrations of the head suspension 2, JP-B-4-8868 proposes adhering a damper 4 to a head suspension 2 as shown in FIG. 2B, the damper 4 comprising a laminate of a constraint layer and a viscoelastic layer. According to this proposal, the viscoelastic layer sandwiched in between the vibrating head suspension 2 and the constraint layer is deformed with the vibrational deformation of the head suspension 2 to generate internal resistance (molecular friction) As a result, the vibration energy is converted to heat energy, and the vibration energy directly transmitted to the head suspension 2 is reduced greatly.
To secure such vibration damping effects, it is important for the constraint layer to have high rigidity. Usually employed constraint layers include plates of metals, such as stainless steel, and plastic films. The viscoelastic layer is conventionally made mainly of pressure-sensitive adhesives, rubber, and the like.
Discs and disc drives having the above-described constitution are precise parts. Hence, they are liable to suffer from troubles attributed to, for example, corrosion by organic gases. The hard disc drives, in particular, are almost sealed in nature of its structure so that the inside atmosphere is liable to have an increased temperature, and the generated organic gases is liable to be confined, which would accelerate corrosion. Of organic gases, silicone gas is to be deposited on the disc. The disc having silicone deposit will have an increased coefficient of friction, and the heat generated by friction with a head may destroy the memory layer of the disc. This has become an important problem.
Since the above-described damper is stuck to a head suspension on its viscoelastic layer side, the viscoelastic layer is usually made of a pressure-sensitive adhesive, and a release sheet (separator) is temporarily adhered to the viscoelastic layer, which is stripped on use.
Conventional release sheets usually rely on silicone releasing agents for the release properties. However, silicone of the silicone releasing agent is transferred to the viscoelastic layer when the release sheet is removed and will give off silicone gas, which can cause destruction of the memory layer of a disc.
Accordingly, an object of the present invention is to provide a damper for a head suspension which will not cause destruction of the memory layer of a disc attributable to silicone gas and a head suspension having the damper thereon.
In order to accomplish the above object, the present invention provides in its first aspect a damper which is adhered to the head suspension of a disc drive, which comprises a laminate of a constraint layer and a viscoelastic layer, wherein the viscoelastic layer is temporarily provided with a release sheet that is removed on use so that the damper may be adhered to the head suspension, the side of the release sheet in contact with the viscoelastic layer having been treated with a non-silicone releasing agent.
In a highly preferred embodiment, the non-silicone releasing agent is a long-chain alkyl type releasing agent or a fluoroacrylate type releasing agent.
The present invention also provides in its second aspect a head suspension for the head of a disc drive which has on at least a part thereof the above-described damper.
Since the releasing agent of the release sheet adhered to the damper is of non-silicone type, the damper generates no silicone gas while used in a disc drive, not giving rise to such a problem that silicone gas destroys the memory layer of a disc. The above-described preferred releasing agent not only prevents silicone gas generation but exhibits satisfactory release properties equally to silicone type releasing agent.
The term xe2x80x9cnon-silicone (type)xe2x80x9d as used herein means that the releasing agent contains no silicone. The term xe2x80x9csiliconexe2x80x9d as used herein is intended to include all organopolysiloxanes, such as silicone oil, silicone rubber, and silicone resins.